Y. Kudo et al., Correlation between the circadian sleep propensity rhythm and hormonal rhythms under ultra-short sleep-wake cycle, PSY CLIN N, 53(2), 1999, pp. 253-255
The aim of this study was to clarify effects of hormonal and temperature rh
ythms on circadian fluctuations of sleep propensity. Ten healthy females un
derwent 24-h sleep deprivation and entered the circadian sleep propensity a
ssessment setting under the ultra-short sleep-wake schedule. During the exp
eriment, sleep propensity rhythm, rectal temperature, and 24-h serum hormon
e profiles (melatonin, cortisol and thyroid-stimulating hormone) were inves
tigated. The circadian sleep propensity rhythms had two apparent peaks (aft
ernoon and nocturnal peaks) and a trough (nocturnal sleep gate). The timing
s of the nocturnal sleep gate and the nocturnal peak were correlated exclus
ively with temperature and melatonin rhythms (P < 0.05), while that of the
afternoon peak was significantly correlated with habitual wake time and mel
atonin rhythm. These results indicate that the circadian sleep propensity r
hythm is influenced not only by the circadian pacemaker, but also by sleep
habit.